What is the plural of Kiasyd

I'd say it would remain 'Kiasyd'.

Interesting question.

I think there are actually quite few clans which would take an -s to create a plural:

Abominations
Ahrimanes
Assamites
Blood Brothers
Daughters of Cacophony
Followers of Set (Setites)
Gargoyles
Harbingers of Skulls
Malkavians
(but not Malkavian antitribu)

That's it. All other clans take the same word for plural as singular.

Except for Ahrimanes, Assamites, and Malkavians, the -s is easy since the word pluralized is also a common noun. IMO clan Assamite takes a plural -s since it is similar to "assassins." Not sure I can explain Ahrimanes or Malkavians, though I wish I could say for a good reason other than "English is just that way."

Actually pluralising is not 'that' strange and its often to do with the category of the word you are trying to make plural.

1) The original word is 'uncountable'... e.g. sand. The only way to plural this category is if you are handling multiple types of sand. (You have a brown and a white sand; you have 2 sands) 'Uncountable' things often use 'much' as their 'I have heaps of this' word (e.g. I have been given much wheat. or I have much to be grateful about.)

2) The original word is 'countable'... e.g. cat. You usually make this word a plural by adding an 's' (when you don't have to worry about ending words with an s). They are fairly common and when you want to talk about different types of them, you usually need to write 'types of XYZ'. (e.g. I own three types of dog). Their 'large number' word is 'many' because you could in theory sit down and count them (where you wouldn't with 5kg of sand grains).

Imho, "Malkavian" is an substantified adjective, which makes it eligible for the -s plural ending.
Ventrue, Tremere, Brujah, Giovanni (which has already a plural ending), Nosferatu, .. are the name of the breeder, and are used as qualifiers. "Ventrue" == "Ventrue vampire", hence the plural: "Ventrue vampires".


However, there seems to be a flaw with Ahrimanes (who should've been "Ahrimen", just for the fun of it).